だれの is used when asking about who the owner of some object is. An example of this would be "これはだれのかばんですか。" meaning "Whose bag is this?"かばん -- bag

The particle も can be used to replace particles in repeated sentences. It is sort of like saying "too" or "also." Here is an example of this:"わたしはアメリカじんです。あなたもアメリカじんです。" translates to "I am American. You are also American."わたし -- Iあなた -- Youアメリカじん -- American

There are other particles that can be replaced with も. If the part following the particle you want to replace is the same, then you can replace it with も; this is easier to do after learning how to use verbs, and about different particles.

じゃないです is another form of です. It is used to say that the subject isn't something, in the form of "X isn't Y." Here is an example:これいぬははやいじゃないです。 which translates to "This dog isn't fast."

There are 3 ways to say じゃないです they are:じゃないですじゃありません -- more conservative speech styleではありません -- formal, appropriate for writeing (the は is read "wa")

Well all of these are correct, it might be easiest to start off learning じゃないです until after you learn short form and informal speech style. This is because the negative short form of です is most similar to じゃないです.

～ね and ～よ are used in the same way. They both get placed at the end of a sentence much like ～か in a question sentence. ～ね is used to ask for conformation about what was being said, and ～よ is used to add assurance about what was being said. Here are two examples:これはにくじゃないですね。 which translates to "This isn't meat, is it?"とんかつはさかなじゃないですよ。 which translates to "Let me assure you that tonkatsu isn't fish."にく -- meatとんかつ -- pork cutletさかな -- fish